The urinary tract is the path that urine follows after it is formed within the kidneys, and involves a left and right ureter, the bladder, and the urethra.
[1] Ultrasound of the urinary tract is performed by a probe placed on the abdominal wall, called a transducer.
If the person is on fluid restriction diet (due to heart, liver or kidney problems), then he can ignore the instruction.
[2] Ultrasound is non-invasive and does not involve radiation, unlike some methods of imaging of the urinary tract such as X-rays or CT scans.
[1] Risks specific to the scan involve: Abdominal obesity, gas within the colon, and barium within the intestines can all impact the accuracy of the test.